Troubleshooting here - there are a number of factors that can affect what you describe: is the needle inserted properly & is it correct for your machine/fabric/thread? What type of thread is being used? Cheap/thin thread has caused such a problem for me in the past. What type of fabric are you sewing on? Can you check the manual to make sure you're doing everything right & that tension is appropriate for fabric/thread? When was the last time you oiled & cleaned your machine?

& you do not say what make/model sewing machine...?

Just some thoughts off the top of my head...

Carolb, thanks for all the factors you thought of. They make sense. I have to admit that I rarely oil or clean my machine. I have a Kennmore basic machine. Since you mentioned about thread, I have a question now. Do different thicknesses of thread for the top and the bottom confuse the flow of sewing action? Should I ALWAYS use the same tread for both the top and the bottom?

I was taught that you can use a thicker thread (or elastic thread) in the bobbin - & adjust the tension accordingly - if you are stitching for shirring. Otherwise they should match.

Somebody may be more savvy about this than I

Do all of the overdue cleaning and maintenance ... a seldom-used machine gets balky because of lack of use.

Test the bobbin tension and fix it if necessary (google it, lots of info about doing this) with your normal sewing thread.

If you are using two different thread thicknesses, you will have to mess with the tension upper and lower until you can get them balanced. Usually adjusting the upper is all you need to do.

Make sure your needle is sharp - if it gets dull the thread doesn't make a nice loop.

very helpful. Thank you lazyGarden

I would think a 14-yo Kenmore has a lot of life in it yet. Do all the spiffing up. And maybe get a tuneup; mine cost under $100.

Oh, thanks. so.... typically, how long in your opinion would a Kennmore last? Just curious

I have a 38 year old Kenmore that still performs flawlessly.